SPHENODONTIANS: NEW INSIGHTS ON THE LEAST KNOWN SOUTH AMERICAN LEPIDOSAURS

APESTEGUIA, S.; GÓMEZ, RAÚL

Buenos Aires

Congreso; XI Congreso Argentino de Herpetologia; 2010

Museo Argentino de Ciencias Naturales Bernardino Rivadavia

The extant composition of the South American lepidosaurian fauna is the result of a complex history in which sphenodontians took a significant part. After decades of scanty record, several discoveries in the last few years, currently under study, have begun to depict a new scenario in which the greater part of the history of Patagonian sphenodontians is yet to be told. Some of these recent discoveries include unpublished Jurassic sphenodontians closely allied to nearly coetaneous species from India. Besides already known early Late Cretaceous large, strictly herbivorous eilenodontine sphenodontians from northern Patagonia, a new dwarf species has been recovered in central Patagonia. In addition, three different sphenodontids, one small- and two large-sized, were recorded in uppermost Cretaceous beds of northern Patagonia. One of them, possibly with marine habits and currently under study, was recently discovered in early Tertiary beds, demonstrating that the group survived the K/P event in South America. The new panorama shows that the Cretaceous non-ophidian lepidosaurian diversity included insectivorous, small native lizards as well as abundant, both herbivorous and animalivorous, mostly large sphenodontians. During the Neogene, possibly after the demise of sphenodontians, lizards diversified and, together with snakes, outlined the extant lepidosaurian fauna.